Air conditioning apparatus



Jan. 2, W4Q. L. G. HUGGINS AIR CONDITIONING APPARATUS Fild Oct. 6, 1936 Fig.2.

INVENTOR LEROY Q. HuQGuNs.

BY ZZZ ATTORNEY lllll Patented Jan. 2, l94

MR CONDITIONIN APPARATU? lLeroy G. Huggins, Mansfield, Ohio, assignor to Westinghouse Electric & Manufacturing Gompany, East Pittsburgh, lla., a corporation of Pennsylvania Application October 6,

v 8 Claims.

My invention relates to. air conditioning apparatus and it has for an object to provide improved apparatus of this kind.

Another object of the invention is to provide apparatus of relatively simple form whereby the humidity of the air in the enclosure being air treated as well as the temperature thereof, may be maintained within desired limits.

In accordance with my invention, I employ a refrigerant evaporator with means for circulating the air to'be conditioned in heat exchanging relation therewith. First and second refrigerant compressors are provided for circulating refrigerant through the evaporator. A thermostat is adapted to effect operation of one compressor in response to a high temperature of the air in the enclosure, and a humidostat is adapted to effect operation of both compressors in response to a high humidity condition of the air.

When only one compressor is operating, it is unable to efiect as low a pressure of the refrigerant in the evaporator as when both compressors are operating. Accordingly, the evaporator operates at higher temperature and the air passing over it. is cooled-approximately only to its dew point. Most of the heat removed from the air, therefore, is sensible heat.

When both compressors are operating, they are able to effect a lower ,pressure and temperature of the refrigerant in the evaporator. In this case, the air is cooled to a much lower temperature, materially below the dew point of the entering air, so that a substantial amount of latent heat as well as sensible heat is also removed from the air, and both cooling and dehumidification are efiected.

The invention is particularly applicable to unit type air conditioners or coolers having a pair of compressors such as is disclosed in the copending application No. 702,376, filed December 14, 1933 and assigned to the-assignee of the present application. It is to be understood, however, that the invention is not limited to self-contained air conditioners but is equally applicable to other forms of air conditioning apparatus.

The foregoing and other objects are effected by my invention, as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. l is a diagrammatic view of an air conditioner arranged in accordance with my invention; and

Fig. 2 is a modified diagram of the control apparatus for the apparatus shown in Fig. 1.

1936, Serial No. 104,166

Referring now to Fig. 1 of the drawing, I show my invention embodied in an air conditioning unit, generally shown at H), and including an evaporator or air cooling unit ll disposed withma chamber I2 that is defined by a casing structure l3. A pair of compressors It and I5, driven by motors l6 and I1, respectively, and connected to a condenser l8, operate to circulate refrigerant through the evaporator H. The compressors l4 and I5 and their respective motors may be enclosed in a hermetic housing H, as shown. The interior of the housing I9 may be connected to the evaporator It by means of a conduit 2| and may form a part of the low side of the refrigerating system. The condenser I8 may be cooled in any suitable manner such as, for example, by water which enters the condenser I8 by the conduit- 22 and is discharged conduit 23. I

The refrigerating system disclosed, operates on the well known compressor-condenser-expander cycle wherein the compressors I 4 and I5 withdraw vaporized refrigerant from the evaporator II through the conduit 2| and the interior of the housing l9 and compress it to a relatively high pressure. The compressed refrigerant is delivered through a conduit 24 to the condenser l8, wherein it is cooled by the water and is condensed. Liquefied refrigerant passes from the condenser [8 to a reservoir 25 through a conduit 26 and thence to the evaporator II by means of a conduit 21.

A suitable expansion device 28 is arranged in the conduit 21 for controlling the fiow of the condensed refrigerant to the evaporator H and for reducing the pressure thereof. The device 28 may be of any suitable type but it is preferably a therefrom through thermostatic expansion valve wherein the fiow of refrigerant to the evaporator II is controlled in response to the refrigerant pressure prevailing in the evaporator and to the temperature of the refrigerant leaving the same. These two controlling influences cooperate to regulate the admission of refrigerant to the evaporator I! so that a substantially constant amount of superheat is present in the refrigerant vapor leaving the evaporator H. As the operation of expansion devices of this type are well known in the art, no further description of their construction or operation is deemed necessary.

Air to be conditioned is translated from the enclosure through inlet openings 31 by a fan 32 and is returned to the enclosure through an opening 33, after traversing the air cooling evaporator ll. Suitable filters, not shown, may be provided in the openings 3| or 33 for cleansing the air passed therethrough.

. 31 and, preferably, leading to the conductor 34.

The thermostat 35 may be of any well known type responding to the dry bulb temperature of the air and operates to open and close the conductor 34 in response to relatively low and high temperature values, respectively. The humidity-respon-- sive instrument 31 may be responsive to the relative humidity of the air or to the wet bulb temperature thereof. In the present description, it

will be assumed that this instrument 31 reflects the relative humidity of the air and opens and closes the conductor 36 in response to relatively low and high values of the humidity, respectively.

A disconnecting switch 38 may be provided in the conductor L1 for rendering the apparatus active or inactive, as desired.

Assume the apparatus is rendered active by the closure of switch 38 and that the temperature of the air in the enclosure has risen to a value of say 75. The thermostat 35 closes the circuit to the motor I6 which circuit includes the conductor L1, switch 38, thermostat 35, conductor 34, winding of motor I6 and conductor L2. Accordingly, operation of the compressor I4 is initiated for circulating refrigerant through the refrigerant circuit including the evaporator II. Circulation of water for cooling the condenser I8 may be effected in any well known manner,

The fan 32 may be controlled in any suitable manner and operated continuously for ventilation during periods when the evaporator II is inactive. As refrigerant is evaporated in the evaporator II, the air circulated by the fan 32 and, therefore, at relatively high suction pressure and temperature.

Assume now that the temperature of the air being treated rises above 15 and that the compressor I4 is operated. If the relative humidity increases above a predetermined value, due to the addition of water vapor to the air or to the cooling thereof by the operation of the first compressor I4, the humidostat 31 closes the conductor 36 and the second compressor I 5 operates in parallel with the compressor I4 for circulating refrigerant through the evaporator II. ingly, a lower pressure and temperature prevail in the evaporator II so that the air is cooled to a greater degree and a substantial portion of the cooling effect is efiective for the removal of latent heat.

From the foregoing, it will be apparent that, when the air being cooled is relatively dry, only a single compressor is operated to depress the temperature thereof and, when the vapor con- Accordtent of the air is relatively high, both of the compressors operate. In the first case, the evaporator is operated at a relatively high temperature for the abstraction of principally sensible heat from the air and in the second case, it is operated at a lower temperature for the removal of latent heat.

There may be occasions when the operation of a single compressor is insufficient to reduce the sensible heat present in the air and that the operation of the second compressor is necessary. Accordingly, the humidity-responsive instrument 31 may be paralleled by a second thermometer 39, that is set for effecting circuit closing operation at a higher temperature than the thermostat 35. With this arrangement, both motors I6 and I1 may be energized for operating their respective compressors when the temperature of the air in the enclosure has risen to a predetermined value, independently of the humidity-responsive instrument 31.

In the foregoing, the humidostat 31 is effective to control the second compressor I5 only during periods when the thermostat 35 is closed in response to a high temperature of the air being treated. I have shown in Fig. 2, an embodiment of my control wherein the humidostat may effect -operation of the compressors during periods when the thermostats 35 and 39 are satisfied. In this embodiment, the thermostats 35 and 39 are' connected in parallel for controlling the operation of their respective motors I6 and I1; the latter being started sequentially as thermostats 35 and 39 successively close.

The humidostat 31 is operative to initiate operation of both motors I6 and I1 and their respective compressors I4 and I5, independently of the thermostats 35 and 39, when the relative humidity of the air attains a predetermined value. The humidostat 31 controls a circuit 4| that includes a relay .42 having main switches 43 and 44 connected in parallel with the thermostats 35 and 39, respectively. Accordingly, when the relative humidity of the air increases to a predetermined value, the relay 42 is energized by the closure of the humidostat 31 and both motors I6 and I1 are energized by the closure of switches 43 and 441 Both compressors I4 and I5 are effective for the circulation of refrigerant and the pressure and temperature of the evaporator II is such that latent heat is removed from the air. During this operation, the thermostats 35 and 39 may be open and the cooling of the air is effected because of the high moisture content thereof. 4

In order that the temperature of the air in the enclosure be not depressed to an uncomfortable degree during the operation of the apparatus by the action of the humidostat, a limiting thermostat 45 may be connected in the conductor 4I in series with the humidostat 31 for controlling the energization' of the relay 42 and the motors I6 and I1. The termostat 45 is normally closed and opens when the temperature of the air in the enclosure has been depressed to a predetermined low value of for example. Openditioning apparatus in which variable quantities '1 claims.

air for efiecting operation.

of refrigerant are circulated and the temperature of the evaporator is varied in response to predetermined temperature and humidity conditions, whereby substantially all of the heat removed from the air at one time is sensible heat and, at another time, sensible and latent heat are removed.

While I have shown my invention in two forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended What I claim is:

1. In apparatus for conditioning air, the combination of air cooling means including first and second elements for circulating refrigerant in heat exchanging relation with the air to be conditioned, means responsive to a predetermined temperature of the air for effecting operation of, one of said elements, whereby limited cooling of the air is eifected, and means responsive to a predetermined condition of the humidity of the of both of said elements, whereby maximum cooling of the air is efiected.

2. In apparatus for conditioning air, the combination of air cooling means including first and second compressor elements for circulating refrigerant in heat exchanging relation with the air to be conditioned, means responsive to a predetermined temperature of the air for efiecting operation of one of said compressor elements, whereby the air to be conditioned is principally cooled above its dew point, and means responsive to a predetermined condition of humidity ot the air for effecting operation of both of said compressor elements, whereby the air to be conditioned is cooled below its dew point.

3. In apparatus for conditioning air, the com.- bination of air cooling means including first and second compressor elements for circulating refrigerant in heat exchanging relation with the air to be conditioned, a

thermostat responsive to the temperature of the air, and an instrument responsive to a condition of humidity of the air, said first and second compressor elements being controlled, respectively, by said thermostat and said humidity responsive instrument.

4. In apparatus for conditioning the air in an enclosure, the combination of means for translating air to the enclosure, an evaporator for cooling the air prior to its admission to the enclosure, first and second compressor elements for circulating refrigerant through the evaporator,

' means responsive to a predetermined temperature of the air in the enclosure for effecting operation of the first compressor element, and means responsive to a predeterminedvalue of the humidity of the air in the enclosure for efiecting operation of the second compressor element during periods when the first compressorelement is operated by the temperature responsive means.

5. In apparatus for conditioning air, the combination of an air cooler, first and second compressor elements for circulating refrigerant through the cooler, means for translating the air to be conditioned in heat exchanging relation with the air cooler, a thermostat responsive to the temperature of the air, an instrument responsive to a humidity condition of the air, and electrical means controlled by the thermostat and said instrument and operative to efiect operation of the first compressor element when the thermostat calls for cooling and to efiect operation oi. both compressor elements when the humidity responsive instrument calls for a reduc-' tion in the vapor content of the air.

6. In air conditioning apparatus for condition- I ing the air in an enclosure, the combination of an evaporator, a fan for withdrawing air from the enclosure and for translating it in heat exchanging relation with said evaporator, means for delivering the air cooled by the evaporator to the enclosure, first and second compressors for circulating refrigerant through the evaporator,

means responsive to the temperature oi the air within the enclosure for controlling the operation of said first compressor, and means responsive to the humidity of the air in the enclosure for controlling the operation of. the second compressor, said temperature-responsive and humidity-responsive means being so arranged that operation of the second machine is always accompanied by operation of the first machine.

7. In air conditioning apparatus, the combination of an evaporator, means for conveying air over said evaporator a plurality of. compressors for withdrawing vapor from said evaporator to efiect vaporization of refrigerant therein, means responsive to a predetermined maximum temperature for effecting operation of one compressor, and means responsive to a predetermined maximum temperature and a predetermined maximum value of humidity for efiecting operation of two compressors.

8. In air conditioning apparatus, the combination of an evaporator, means for conveying air over said evaporator, a plurality of. compressors for withdrawing vapor from said evaporator to effect vaporization of refrigerant therein, means responsive to a. predetermined maximum temperature for efiecting operation of one compressor, and means controlling theoperation of at least one other compressor and efiective to increase the number of compressors in operation to two in response to a predetermined high humidity condition.

- LEROY G. HUGGINS. 

